1. Field of the Invention
This invention relates to an image recognition system for recognizing an image by bi-level picture processing. More particularly, it relates to an image recognition system wherein recognition of the presence, shape, orientation and so on of an article is enabled by constituting the system in such a way that master data consisting of points designated by an operator are registered in the system in order to teach the system important features of the article, and data of a candidate article are compared with the master data during execution of a recognition algorithm.
2. Description of the Prior Art
In manufacturing certain goods, for example electronic appliances, parts are sometimes arranged in a row on a palette and forwarded on a belt conveyor for assembly. Occasionally some of the parts on the palette are missing because of a malfunction of a machine for arranging such parts or for some other reason.
To deal with this problem, a system has been proposed wherein an image of parts on a palette is picked up by a video camera, and the resulting video signals are processed in order to detect whether any parts are missing. For this purpose it is not necessary to discern minute structural details; it is only necessary to determine whether or not all of the required parts are present. Accordingly, such video signals may be bi-level signals of black and white levels, and processing of a picture image may be made on the basis of such bi-level signals.
However, in most conventional systems of the type mentioned, the user cannot set the conditions for judgment; accordingly, such conventional systems are inflexible and difficult to use. For example, since the reference level for discriminating between white and black of a candidate article cannot be set by the user, it is not possible to make appropriate allowance for variations in coloration and illumination of a candidate article. Accordingly, the reliability in judgment is so low that errors readily occur.
Further, pattern matching for recognizing the shape of an article is performed commonly by a template matching method. However, since in the template matching method a master pattern registered in advance is scanned over an entire area of a television picture plane in a search for a coincident pattern, it is necessary, for example, in the case of recognition of characters, to scroll the picture plane character by character. Accordingly, a great deal of time is required for recognition.
Besides, there is a practical limit to the number of different sizes and shapes of master patterns Accordingly, the conventional systems lack versatility and are not easy to use.